CHARACTERIZING THE DROUGHT DEVELOPMENT IN THE PHILIPPINES USING MULTIPLE DROUGHT INDICES DURING THE 2019 EL NIÑO

Abstract. Drought events in the Philippines have resulted in a significant loss in crop production. This study investigated the drought development during the 2019 weak El Niño using different drought indices at a country and local scale. Satellite data from MODIS were used to derive Normalized Difference Vegetation Index (NDVI) anomaly, Vegetation Health Index (VHI), and Standardized Vegetation and Temperature Ratio (SVTR), while TRMM was used for the Standardized Precipitation Index (SPI). These indices were compared with crop production data at national scale and crop damage reports at local scale. The results showed consistency in the spatiotemporal variation of drought events, where drought peak occurred during March to April in most indices and indicators. Based on the values of SPI, the areas with rainfall deficit increased from January to April (25% to almost 100%), but looking at vegetation stress, around 50% was affected, as seen by SVTR and VHI. Yield loss during the first and second quarter after the El Niño peak increased up to 20%, especially in the western region in the Philippines. Overall findings demonstrate the relevance of utilizing multiple drought indices and indicators that characterize drought evolution, from drought onset to the peak of agricultural drought, which is essential in developing a robust drought metric for the Philippines.